Field of the Invention
The present invention relates to a ferroelectric crystal film including a seed crystal film, an electronic component, a manufacturing method of the ferroelectric crystal film, and a manufacturing apparatus therefor.
Description of a Related Art
<Manufacturing Method of a Ferroelectric Crystal Film Using Epitaxial Growth>
FIG. 12 is a cross-sectional view for explaining a conventional manufacturing method of a ferroelectric crystal film.
A Pt film 102 having an orientation in (100) is formed over a substrate 101 such as a 4-inch wafer. Successively, a Pb(Zr, Ti)O3 film (hereinafter, called a “PZT film”) 103 is grown epitaxially over this Pt film 102 by a sputtering method. An example of the sputtering condition at this time is as follows.
[Sputtering Condition]
Apparatus: RF magnetron sputtering apparatus
Power: 1,500 W
Gas: Ar/O2 
Pressure: 0.14 Pa
Temperature: 600° C.
Film deposition rate: 0.63 nm/sec
Film deposition time: 53 min
By the above epitaxial growth, the PZT film 103 is formed over the Pt film 102 having a thickness of 2 μm. This PZT film 103 has a preferred orientation in (001) as shown in FIG. 13 and has an extremely preferable crystalline property.
In the above conventional manufacturing method of the ferroelectric crystal film, the film deposition rate of the epitaxial growth by the sputtering is low, and therefore the film deposition time becomes long and this method is not suitable for volume production.
Further, the temperature in the sputtering is as high as 600° C., and therefore a vacuum chamber of the apparatus needs to be kept at a high temperature for a long time and a heavy load is applied to the apparatus.
Further, it is known generally that the PZT film deposited by the epitaxial growth has a large leak current density, and therefore withstand voltage is low.
<Manufacturing Method of a Ferroelectric Crystal Film Using a Spin-Coat Coating Method in which a Precursor Solution is Used>
Next, another conventional manufacturing method of the ferroelectric crystal film will be explained (e.g., refer to Patent Document 1 (WO2006/087777)). This another conventional manufacturing method of the ferroelectric crystal film forms the PZT crystal film 103 shown in FIG. 12 by a spin-coat coating method, not by the sputtering method. Details will be explained below.
A PZT precursor solution is spin-coated on the Pt film 102 by a spin coater. At this time, the spin-coater is spun at 1,500 rpm for 20 sec after spinning at 500 rpm for 5 sec. The PZT precursor solution is a precursor solution containing a metal compound including some or all the component metals of the PZT crystal and partial polycondensate thereof in an organic solvent, and a solution having a PZT concentration of 25 weight % (Zr/Ti=52/48) and including 20%-excessive Pb.
Successively, this coated PZT precursor solution is heated on a hot plate to 250° C. and kept at this temperature for 30 sec to be dried for water removal, and then further heated to 450° C. on the hot plate which is kept at a high temperature, and kept at this temperature for 60 sec for temporary calcination.
The above spin coating, drying, and temporary calcination are repeated five times and a five-layer PZT amorphous film is formed.
Successively, annealing processing is performed for the PZT amorphous film after the temporary calcination by keeping the PZT amorphous film at a temperature of 700° C. for 3 min in an oxygen atmosphere of 10 atm using a pressure-type lamp annealing apparatus (RTA: Rapid Thermal Anneal), and thereby PZT crystallization is performed. This crystallized PZT film has a perovskite structure, and the film deposition rate is 2.65 nm/sec including the PZT crystallization from the spin coating of the PZT precursor solution and the film deposition time is 13 min.
The PZT crystal film is formed having a thickness of 2 μm on the Pt film by the spin-coat coating method using the above precursor solution, and this PZT crystal film has orientations in (001) and (110) as shown in FIG. 14.
Although the (001) orientation and the (110) orientation are detected in the PZT crystal film manufactured using the above method and the (100) orientation of the foundation Pt film is not transferred completely, the spin-coat coating method has an advantage that basically a coating capability does not depend so much on a wafer size and this method is easily accommodated to large area coating by a slight change of a coating condition, and therefore the spin-coat coating method is a coating method suitable for volume production. On the other hand, the PZT crystal film by the above epitaxial growth, while having an advantage that the (100) orientation of the foundation Pt film transferred completely, has a considerably low film deposition rate compared to the spin-coat coating method and therefore has a problem to be solved for volume production.